National standard

1. Vibration acceleration national standard (commonly known as Z standard)

This standard was formulated relatively early to determine the quality level of the bearing by measuring the vibration acceleration value when the bearing rotates. It is divided into three quality levels from low to high, Z1, Z2, and Z3. At present, domestic bearing manufacturers are still using the vibration acceleration value to measure the quality of the bearing, which simply reflects the fatigue life of the bearing.

2. Vibration speed standard (commonly known as V mark)

Since the original vibration acceleration standard has not been abolished, the standard was issued by the Ministry of Machinery Industry. It was formulated with reference to European standards and combined with my country’s actual conditions and needs. It is used to detect the vibration speed of the bearing to classify the quality level of the bearing (equivalent to the national standard). Divided into five quality levels: V, V1, V2, V3, and V4. The quality grades of various ball bearings from low to high are V, V1, V2, V3, and V4; the quality grades of roller bearings (cylindrical and cone) from low to high are V, V1, V2, and V3.

It reflects the quality of the bearing by detecting the vibration b speed of the bearing in different frequency ranges (low frequency, medium frequency, high frequency). It can be roughly analyzed whether the bearing has geometrical size problems (such as steel ring ellipse), the quality of the raceway/rolling element, and the quality of the cage. Compared with the inspection of the bearing quality by vibration acceleration, it has been significantly improved. At present, domestic bearings exported to Europe, my country's military and aerospace industry have carried out bearing quality testing in accordance with this standard. At the same time, testing the quality of European imported bearings and distinguishing counterfeit imported bearings provides a feasible means.
Bearing quality testing has two parallel standards. Bearings with a very high "Z-mark" quality level may not have good quality performance when tested with "V-mark", and there is no corresponding relationship between the two. This should be paid special attention to in the quality inspection of bearings.